SNES console problem

[lidnariq]

They're these: wikimedia:aluminum electrolytic capacitor cutaway view

[qwertymodo]

Also, since I have no kind of electrical engineering background, what are "caps"? are they these things? What do they do? What do they contain, some sort of battery acid? (I looked up electronic caps on Google, but I just got some sort of company.)

Those are all electrolytic capacitors. The silver and black ones are just surface-mount versions, while the ones with the blue and white "wrappers" are through-hole. Functionally, they are identical.

To visualize what they do, think of them like a really small battery that takes maybe a second to charge or discharge. What happens is that the voltages on the various signals or power lines aren't always "clean" meaning they will vary up or down from their intended voltages, either due to radio signals being picked up by the copper traces like an antenna, or just due to the imperfect nature of the components, or various other reasons. One of the two main issues that are overcome by capacitors are large, singular fluctuations that can be caused by things like plugging in a controller, because the instantaneous change of suddenly having to supply power to a whole new device can actually cause the power rails to drop in voltage because they can't immediately adjust to the change. So when that happens you put a really big capacitor on the power line to "help" the power supply to maintain it's proper level. The "battery" will only last less than a second before it's completely discharged, but that's long enough for the power supply to get back to where it needs to be, at which point the power supply will "recharge" the capacitor so it's ready in case it happens again. The second issue is radio interference (which isn't always actual radio signals, but every electronic device generates electromagnetic fields which are basically the same thing). This interference is really fast, but not very large in terms of the amount that the voltage changes. However, sometimes this "noise" is actually enough to cause glitches, so for that they use really small capacitors which are basically constantly "charging" and "discharging" in order to smooth out the rapid up-and-down on the data lines.

Electrolytic vs ceramic capacitors are just two different kinds made of different materials which each have their pros and cons for specific applications (through hole ceramic caps typically look like this but there are variations). Ceramic caps can't be reasonably made in large sizes, so they are typically used for the second scenario, for filtering small high frequency signals, whereas electrolytic capacitors can be made in much larger sizes, but are much more prone to failure over time because of how they are made. For that reason, it's much more likely that the electrolytics need to be changed rather than the ceramics. Electrolytic capacitors don't contain "battery acid", they store their small amount of charge on a plate, much like if you have ever rubbed a balloon against your head and stuck it to the wall from the static, the electricity is stored on the surface of the balloon because it has no conductive path to ground.

[Drew Sebastino]

Those are all electrolytic capacitors

Electrolytic capacitors don't contain "battery acid"

Wait a minute, then why do people always complain about the capacitors ruining old consoles? the picture right there is of the SNES motherboard (only board, really) and, like you said, they don't contain any battery acid, so they shouldn't really break the console if they do, you just have to replace them more often, which I can't imagine being the hardest thing to do. (I imagine it would be harder to replace the ones that are stuck to the circuit board, then the other ones where you could probably solder the two "poles" onto the board.)

[lidnariq]

Electrolytic capacitors don't contain battery acid, but they do contain an electrolyte. In the case of the cheap and widespread aluminum ones, that's a liquid (and therefore capable of leaking). It's often not the nicest of chemicals, either. Wikipedia has a huge article about it, too.

[Khaz]

So I did some more poking at my broken SNES today out of curiosity... I don't know how I ever thought Dragon View was the only game that's broken, because I'm getting the same kind of thing on everything I try long enough now.

Most common problem is BG layers just plain disappearing, turning solid black. Occasionally some garbage appears on screen. Sometimes sprites disappear too - Mario disappeared between rounds of Mario Kart, turning it into an awkward first-person-perspective game. What is REALLY bizzare though, is that in Dragon View the sprites of all the objects on the world map jitter around. They'll flicker back and forth, sometimes not just a pixel or two but nearly half a screen away, while you're standing still.

All the while the games run perfectly fine, it's just a graphical problem. Something inside the PPU is shot...

Is it possible to repair a problem like this? Can you just find and swap out a chip maybe, if someone still makes them?

EDIT: JUST as I say that, I notice that mario kart seems to have gone into an infinite loop after the race and isn't responding to controller input. I don't know what's going on anymore.

Yeah, Mario Kart is reeeally broken. I finished the second race, got a "Game Over", then another race starts but I can't move...